An Expression Field doesn't display an expression evaluation result when the form or page read-only mode is enabled within a survey JSON definition

[JaneSjs]

T21284 - Expression question's value is not visible if the form is in view mode (read-only state)
https://surveyjs.answerdesk.io/internal/ticket/details/T21284

---

Consider the following demo: View Plunker.

{
  "pages": [
    {
      "name": "page1",
      "elements": [
        {
          "type": "text",
          "name": "question1",
          "defaultValue": "My Answer"
        },
        {
          "type": "expression",
          "name": "question2",
          "expression": "'Hello World!'"
        }
      ]
    }
  ],
  "mode": "display"
}

When "mode": "display" is enabled within the survey JSON definition, an expression field is empty:

However, if you enable the read-only mode using the SurveyModel object instance, the expression displays the result:

This issue also occurs when a page's readOnly option is enabled within the survey JSON definition.